Spacers will be all the same among just about all recent BMWs (and even the vast majority of past ones as well).
BMS are affordable and popular...
http://www.burgertuning.com/BMW_wheel_spacers.html
*Note, the spacer is the same between the E and F series cars, but the lugs are a different thread pitch.
They go on sale pretty regularly.
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'02 S54 M3 (500/500 GC/Koni)
'08 N54 135 (JB4, DCI, BMW PS/Bilstein B6s, H&R M3 FSB, Strongflex FCABs)
'14 N55 X1 (JB4, BMS DP, BMS Intake, Alpina TCU reflash, H&R Sports, Bilstein B6s, E93 M3 RSB, Strongflex FCABs, baby seat)
'08 N54 535xi touring (Bilstein B6s, Downpipes, MHD tune, baby seat)